RT Journal Article SR Electronic T1 Comparison of Trunk Injected and Soil Applied Macronutrients JF Arboriculture & Urban Forestry (AUF) FD International Society of Arboriculture SP 322 OP 324 DO 10.48044/jauf.1991.071 VO 17 IS 12 A1 Smiley, E. Thomas A1 Fraedrich, Bruce R. A1 Booth, Donald C. YR 1991 UL http://auf.isa-arbor.com/content/17/12/322.abstract AB Macronutrients (N,P,K,) deficient willow oaks (Quercus phellos) grown in parking lot islands were fertilized by trunk or soil injection. Foliar nitrogen levels improved significantly in soil fertilized trees. Foliar color improved most in the soil fertilized trees and not at all in the controls.